Keratoconus is an eye ectasia that affects the cornea causing distortion of vision. Corneal crosslinking promoted by riboflavin photo-stimulated at 365 nm is a treatment used successfully to block the keratoconus progression. In this study, we characterize rabbit corneas subjected to enhanced crosslinking using different vegetable extracts prepared from Stryphnodendron adstringens (Mart.) Coville bark by differential scanning calorimetry. The extracts tested in this study were: aqueous, ketonic, ethanolic, ethyl acetate and hydroalcoholic, which revealed high levels of polyphenols, such as proanthocyanidins. The corneas, obtained from the slaughter rabbits, were divided into groups: control (consisting of untreated corneal samples) and S. adstringens, where the samples were subjected to 4% vegetable extracts for 2 h. The DSC profiles of the corneas were obtained in nitrogen atmosphere. The results showed that temperature and enthalpy of denaturation of the corneal samples treated with S. adstringens were higher than the control group. The control group presents temperature and enthalpy values of 59.8 ± 1.1 °C and 24.6 ± 2.7 J g -1 , respectively. After crosslinking with ketone extract, the values were 90.1 ± 1.1 °C and 39.9 ± 2.7 J g -1 . These results show that S. adstringens is efficient to increment the crosslinking level of the corneas.

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Background Tuberculosis (TB) caused by Mycobacterium tuberculosis has a high prevalence in Brazil (Global tuberculosis report 2020. Geneva: World Health Organization; 2020). The ethambutol-induced optic neuropathy damage is partly reversible, making its early diagnosis essential to reduce permanent visual damage. Purpose To observe alterations in the computerized campimetry, Ishihara test and visual acuity secondary to rifampicin, isoniazid, pyrimethamine, ethambutol (RHZE) treatment. Methods Patients undergoing treatment with RHZE at the tuberculosis service of the Federal University of São Paulo were recruited from March 2019 to December 2020. The best-corrected visual acuity (VA) measurements, Ishihara test and visual fields were performed at baseline, monthly, until 2 weeks after treatment. Results Twenty-five patients were included. The VA decreased significantly (P = 0.0129) post-treatment compared to month 1. The mean deviation (MD) did not decrease significantly (P > 0.05); the pattern standard deviation (PSD) decreased post-treatment compared to month 1 (P = 0.0371). Changes in the Ishihara test increased significantly (P < 0.0001) in the second month. Conclusion The VA and PSD decreased significantly after RHZE treatment. Changes in the Ishihara test were observed in the second month. Trial registration: The Research Ethics Committee of Federal University of São Paulo, Paulista School of Medicine approved the study in March 2019. CAAE 04297018.4.0000.5505.